Question

please answer this question why they r having same structure? how can we define in their structure

Answer 1

No, there is not methanone compoundexist.

but methanal is exist and the formula of methanal is HCHO.

In organic compound|lang=de terms the difference between methanal and methanol is that methanal is methanal, formaldehyde while methanol is methanol.

As nouns the difference between methanal and methanol is that methanal is methanal, formaldehyde while methanol is methanol.

Answer 2

the second structure is not possible as the ketone group carbon should be attached to other carbon only it means both the valency must be satisfied by other carbon atom